RADIOMETER ABL800 FLEX, Reference Manual

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ABL800 FLEX Reference Manual 1. Potentiometric measuring principles
pH electrode,
Continued
Measurement The sample pH is calculated as follows:
pH(sample) =
E(pH, sample) E(pH, Cal1)
61.5 Sens(pH)
pH(Cal1)
−
− ×
+
Corrections The measured pH value is then corrected for systematic deviations from the
reference method using the following equation:
Equation A:
pH(sample,corr.) = A
0
× pH(sample) + A
1
where:
pH(sample) = uncorrected pH value of the sample
pH(sample,corr.) = corrected pH value of the sample.
A
0
= instrument-dependent correction factor
A
1
= instrument-dependent cut-off
Equation A+:
When an additional correction is needed, equation A is first used together with the
constants for the FLEXMODE (195 and 165
µ
L, no message) mode. Then the
obtained results are put back into equation A as pH(sample) and then treated again,
using the constants for the specific sample handling to obtain the corrected value.
Corrections are as follows:
ABL8XX
FLEX
Mode A
0
A
1
Equation
35/25/15 S195 0.9964 0.0150 A
S95 0.9964 0.0150 A
S85 0.9964 0.0150 A
C95 1.007
−
0.053
A+
C55 1.025
−
0.1880
A+
FLEXMODE (no message) 0,9964 0.0150 A
FLEXMODE (message 874) 1.007
−
0.0530
A+
FLEXMODE (message 873) 1.007
−
0.0530
A+
FLEXMODE (message 872) 1.0216
−
0.1639
A+
FLEXMODE (message 871) 1.025
−
0.1880
A+
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